Question

我遇到查询问题，必须计算行数并返回数字。关键是我需要最近24小时的数据，除以一小时的时间。我已经24次使用UNION ALL完成了这个查询，但是有超过800行的SQL单一查询（令人惊讶的是它只需要3秒）。我知道我可以按时间分组，但不知道如何正确地做到这一点。我坚信同等查询可能只在大约20-30行SQL中。我会感谢任何线索。在这里，您可以对我提到的那些进行简化查询。

长查询（使用UNION ALL）：

DECLARE @CurrentTime datetime = GETDATE();

--Data from 1 hour
SELECT
----Time
(SELECT CONVERT(VARCHAR(5), (DATEADD(HOUR, -1, @CurrentTime)), 114)) AS [Time],

----Count on 1st table
(SELECT COUNT(T1.[TableFirstId])
FROM [dbo].[Table1] AS T1
WHERE T1.[IncomingDate] BETWEEN (DATEADD(HOUR, -1, @CurrentTime)) AND @CurrentTime) AS [CountT1],
----Count on 2nd table
(SELECT COUNT(T2.[TableSecondId])
FROM [dbo].[Table2] AS T2
WHERE T2.[IncomingDate] BETWEEN (DATEADD(HOUR, -1, @CurrentTime)) AND @CurrentTime) AS [CountT2],
----Count on 3rd table
(SELECT COUNT(T3.[TableThirdId])
FROM [dbo].[Table3] AS T3
WHERE T3.[IncomingDate] BETWEEN (DATEADD(HOUR, -1, @CurrentTime)) AND @CurrentTime) AS [CountT3]

UNION ALL

--Data from 2 hours
SELECT
----Time
(SELECT CONVERT(VARCHAR(5), (DATEADD(HOUR, -2, @CurrentTime)), 114)) AS [Time],

----Count on 1st table
(SELECT COUNT(T1.[TableFirstId])
FROM [dbo].[Table1] AS T1
WHERE T1.[IncomingDate] BETWEEN (DATEADD(HOUR, -2, @CurrentTime)) AND (DATEADD(HOUR, -1, @CurrentTime))) AS [CountT1],
----Count on 2nd table
(SELECT COUNT(T2.[TableSecondId])
FROM [dbo].[Table2] AS T2
WHERE T2.[IncomingDate] BETWEEN (DATEADD(HOUR, -2, @CurrentTime)) AND (DATEADD(HOUR, -1, @CurrentTime))) AS [CountT2],
----Count on 3rd table
(SELECT COUNT(T3.[TableThirdId])
FROM [dbo].[Table3] AS T3
WHERE T3.[IncomingDate] BETWEEN (DATEADD(HOUR, -2, @CurrentTime)) AND (DATEADD(HOUR, -1, @CurrentTime))) AS [CountT3]

UNION ALL

--Data from 3 hours
SELECT
----Time
(SELECT CONVERT(VARCHAR(5), (DATEADD(HOUR, -3, @CurrentTime)), 114)) AS [Time],

----Count on 1st table
(SELECT COUNT(T1.[TableFirstId])
FROM [dbo].[Table1] AS T1
WHERE T1.[IncomingDate] BETWEEN (DATEADD(HOUR, -3, @CurrentTime)) AND (DATEADD(HOUR, -2, @CurrentTime))) AS [CountT1],
----Count on 2nd table
(SELECT COUNT(T2.[TableSecondId])
FROM [dbo].[Table2] AS T2
WHERE T2.[IncomingDate] BETWEEN (DATEADD(HOUR, -3, @CurrentTime)) AND (DATEADD(HOUR, -2, @CurrentTime))) AS [CountT2],
----Count on 3rd table
(SELECT COUNT(T3.[TableThirdId])
FROM [dbo].[Table3] AS T3
WHERE T3.[IncomingDate] BETWEEN (DATEADD(HOUR, -3, @CurrentTime)) AND (DATEADD(HOUR, -2, @CurrentTime))) AS [CountT3]

UNION ALL

--(etc...)

那个查询给了我类似的东西：

Time    |   CountT1   |   CountT2   |   CountT3

21:05   |   3215467   |   3456364   |   3234234

20:05   |   2253221   |   3123123   |   3238291

19:05   |   1231467   |    1232342  |   1123123

18:05   |   3112412   |    6712353  |   1233124

17:05   |   1242141   |   1241142   |   4112426

16:05   |   3123467   |   3456364   |   3234234

15:05   |   3215467   |   3412334   |   3231234

14:05   |   3324467   |   3456123   |   2312334

13:05   |   3215467   |   3456364   |   1112310

12:05   |   3215467   |   3456364   |   1231234

11:05   |   3123127   |   3456364   |   3234234

10:05   |   3215467   |   3456364   |   3234234

09:05   |   3215467   |   3456364   |   3234234

08:05   |   3215467   |   3456364   |   3234234

07:05   |   3215467   |   3456364   |   3234234

06:05   |   3215467   |   3456364   |   3234234

05:05   |   3215467   |   2212214   |   3234234

04:05   |   3215467   |   3126542   |   3234234

03:05   |   3215467   |   3123364   |   3234234

02:05   |   3215467   |   3456364   |   3234234

01:05   |   3215467   |   3456364   |   3234234

00:05   |   3215467   |   3456364   |   3123123

23:05   |   3215467   |   3456364   |   3212313

22:05   |   3223424   |   1232163   |   1235321

我需要通过更简单的查询返回相同的结果（想到这样的事情）：

DECLARE @CurrentTime datetime = GETDATE();

--Data from 24 hours
SELECT

----Count on 1st table
(SELECT COUNT(T1.[TableFirstId])
FROM [dbo].[Table1] AS T1
WHERE T1.[IncomingDate] BETWEEN (DATEADD(HOUR, -24, @CurrentTime)) AND @CurrentTime) AS [CountT1],
----Count on 2nd table
(SELECT COUNT(T2.[TableSecondId])
FROM [dbo].[Table2] AS T2
WHERE T2.[IncomingDate] BETWEEN (DATEADD(HOUR, -24, @CurrentTime)) AND @CurrentTime) AS [CountT2],
----Count on 3rd table
(SELECT COUNT(T3.[TableThirdId])
FROM [dbo].[Table3] AS T3
WHERE T3.[IncomingDate] BETWEEN (DATEADD(HOUR, -24, @CurrentTime)) AND @CurrentTime) AS [CountT3]

FROM [dbo].[Table1] AS T1
GROUP BY DATEPART(HOUR, T1.[IncomingDate])

但它并没有像我预期的那样奏效。是否有人会帮助我理解这一点？并解决我的问题？

Answer 1

此解决方案围绕将IncomingDate截断为您需要的每小时增量，然后在该值上加入子查询。我正在修改您的要求，并要求所有小时增量完全按小时开始，因为这大大简化了查询。我截断使用

CONVERT(VARCHAR(13), IncomingDate, 120)

还有其他方法可以这样做（突出显示here）但如果我们要对这个价值进行分组，那么这个方法似乎更好。要获取一个表的每小时行数，我们有一个这样的查询：

SELECT COUNT(*) AS T1Count,
CONVERT(VARCHAR(13), IncomingDate, 120) AS IncomingDate
FROM Table1 
GROUP BY CONVERT(VARCHAR(13), IncomingDate, 120)

现在我们需要做的就是重复所有3个表，然后在T1.IncomingDate上进行FULL OUTER JOIN。结果如下：

SELECT T1.IncomingDate, t1.T1Count, t2.T2Count, t3.T3Count FROM
    (SELECT COUNT(*) AS T1Count,
    CONVERT(VARCHAR(13), IncomingDate, 120) as IncomingDate
    from Table1 
    group by CONVERT(VARCHAR(13), IncomingDate, 120)) As T1
FULL OUTER JOIN (SELECT COUNT(*) AS T2Count,
                 CONVERT(VARCHAR(13), IncomingDate, 120) as IncomingDate
                 from Table2 
                 group by CONVERT(VARCHAR(13), IncomingDate, 120)) As T2
    ON T1.IncomingDate = T2.IncomingDate
FULL OUTER JOIN (SELECT COUNT(*) AS T3Count,
                 CONVERT(VARCHAR(13), IncomingDate, 120) as IncomingDate
                 from Table3 
                 group by CONVERT(VARCHAR(13), IncomingDate, 120)) As T3
    ON T1.IncomingDate = T3.IncomingDate
order by T1.IncomingDate

请注意

此查询将针对您的所有数据，我希望您的服务器可以处理它。您可以使用一些WHERE子句轻松修剪它。
在没有大量测试数据的情况下，我无法在本地计算机上测试3路全外连接，我懒得创建自己。如果不是，您可以使用this answer进行更好的3路外连接。

Answer 2

此查询将为您提供与使用较少SQL的查询完全相同的结果。

DECLARE @HourTbl TABLE ( HourBegin DATETIME, HourEnd DATETIME)
DECLARE @i INT=0
DECLARE @dtBegin datetime 
DECLARE @dtEnd datetime = GETDATE()

WHILE @i < 24
BEGIN
    SET @i = (@i + 1)
    SET @dtBegin = @dtEnd
    SET @dtEnd = DATEADD(HOUR, -@i, @dtBegin)
    INSERT  INTO @HourTbl
    SELECT   @dtBegin, @dtEnd   
END

;with hourVal (  hourBegin , hourEnd )
as
(

select  hourBegin, hourend
from @HourTbl
)
select CONVERT(VARCHAR(5), hourVal.hourBegin, 114), 
(
select  COUNT(T1.[TableFirstId]) 
from Table1
where T1.[IncomingDate] BETWEEN hourVal.hourBegin, hourVal.hourEnd
),
(
select COUNT(T1.[TableFirstId]) 
from Table2
where T1.[IncomingDate] BETWEEN hourVal.hourBegin, hourVal.hourEnd
)

按小时分组计数（从 - 到）

2 个答案: